Clamping means

ABSTRACT

557,008. Clamps ; dental chair head rests. COWPER, F. M., and AMALGAMATED DENTAL CO., Ltd. March 28, 1942, No.4148. [Class 44] [Also in Group XIV] A flexible jaw clamping device is operated to effect grip by a bolt movable longitudinally by a hand-operated cam pivoted to one end of the bolt and bearing against a roller the spindle of which is mounted on one of the jaws and passes through a slot in the bolt. The invention is described as applied to clamping simultaneously two pivots of a known kind of dental chair head rest comprising a support b pivoted at its lower end to a bracket arm a and at its upper end to the arm c of a head-rest having pads d, the bearings for the pivots a&lt;1&gt;, c&lt;1&gt; being split to provide flexible jaws, a clamping bolt f extending in known manner through the support b as shown. The bolt is adjustably anchored to the lowest jaw b&lt;1&gt; by a flanged nut g bearing against a compression spring h and secured in adjusted position by set screw o. The upper end of the bolt carries the pivoted cam k with operating handle i, the cam shown being of channel section, Fig. 6, to provide two operative surfaces co-operating with a corresponding pair of rollers l on a common spindle m secured in the upper jaw b&lt;2&gt;, the spindle passing through a slot in the bolt to allow the necessary relative movement. To prevent collapse of the support when the clamp is released a sufficient frictional resistance is permanently imposed on the pivot a&lt;1&gt; by screws n adjustably compressing the lower pair of jaws independently of the clamping device.

May 16,1944. .F. M.MCOV\IIPER 2,348,961

CLAMPING MEANS Filed April 6, 1943 Q 2 Sheets-Sheet l Patented May 16, 1944 CLAMPING MEANS I Frank Moore Cowper; Sutton, England, assignor to The Amalgamated Dental London, England Company, Limited,

ApplicationApril 6, 1943, Serial No. 482,043 In Great Britain March 28, .1942

4 Claims.

This invention relates to a clamping device for locking or holding relatively movable members in any desired angular or other relationship to one another, and while it has been particularly designed for the clamping of the head-rests of dental, surgical and like chairs, it may be applied with equal efiect and like advantage to the clamping of other similarly adjustable members of X-ray or other dental or surgical apparatus or of other structures or appliances.

The object of the present invention is to devise a simple and effective clamping means which is not dependent on any toggle mechanism in which a part must be moved over the dead centre with the result that a certain amount of the available clamping pressure is not usefully employed.

According to my invention I effect the clamping means by a clamping bolt movable longitudinally by a cam rotatable by a hand lever pivoted to one end of the bolt.

Further features of the invention will be apparent from the description given hereafter.

The accompanying drawings illustrate one mode of carrying out the invention.

Figure 1 is a rear elevation of one form of clamp in accordance with the invention applied to the head-rest on a dental or like chair.

Figure 2 is a side elevation.

Figures 3 and 4 are sectional views of the clamp of Figure 1 showing the parts in the free and clamping positions respectively.

Figure 5 is an underneath view of the lower part of the clamp of Figure 1, and

Figure 6 is a sectional view of the upper part.

In carrying my invention into effect in one convenient manner, as for example, in its application to the head-rest of a dental or like chair, I form the main part of the apparatus much in the usual manner, that is to say, I provide a bracket (1 slidably adjustable in the chair, and upon this bracket I pivotally mount a support 17, to the other end of which is pivotally mounted an arm 0 having a bifurcated end carrying the pivoted head-rest pads d, or like members.

The ends of the support b to which the bracket a and arm c are pivotally secured are formed as split members 12'?) giving a certain amount of resiliency to the support ends so that when such spring members are drawn together they will firmly clamp the pivots ac of the bracket and arm respectively while when released each of the latter or either of them may be angularly adjusted relatively to one another and then clamped in new positions. Preferably when the parts are thus released for adjustment the upper arm may pivot freely in the supporting member but the lower bracket is held in the support with a slight degree of frictional resistance so that there will be no fear of the support collapsing and thereby causing possible injury to the patient or operator.

For the purpose of effecting the clamping I provide a longitudinal bore e extending from one end to the other of the support and within this I arrange a locking bolt 7, the lower end of which is secured to a nut 9 adjustable in the bottom jaw of the lower clamping member I), and between this nut and an abutment in the support I arrange a suitable helical compression spring h.

The upper end of the bolt pivotally carries a hand lever 11 which is formed with or carries a cam lc adapted to co-operate with a roller (or rollers) Z mounted upon a spindle m secured to the upper jaw of the upper clamping member 12 For convenience I duplicate the rollers I as shown so that one is arranged upon either side of the locking bolt, and the cam is is also duplicated so as to co-operate with the two rollers. The bolt 1 is suitably slotted as shown at to permit of its longitudinal movement relatively to the pin m carrying the rollers Z.

The arrangement is such that when the hand lever i is in its free position shown in Figure 3 the compression spring h moves'the locking bolt so as to release the upper and lower clamping jaws and permit of relative adjustment of the members in the support. When these have been moved to the required position the hand lever is then pressed so that it lies adjacent to the support as shown in Figure 4 and by the co-operation of the cam and. roller means the locking bolt is given a direct longitudinal movement which draws both sets of clamping jaws together and holds the members firmly in their adjusted position.

The slight frictional resistance imposed on the lower pivotal member may be conveniently obtained by means of a screw or screws 11. which, when the hand lever i is in the released or free position, is or are adjusted to draw the lower clamping jaws together to an extent sufficient to impose the degree of resistance required.

For the purpose of adjusting the apparatus the grub screw 0 which normally holds the lower nut g on the locking bolt in position is released and, with the hand lever in the open or free position, the said nut is adjusted on the locking bolt so as to allow of the proper tightening of the upper and lower clamping elements when the said hand lever is in its closed position.

I claim:

1. A clamping device comprising a support, resilient clamping jaws at the opposite ends of said support, a locking bolt movable longitudinally in said support and connected at one end with one of said jaws, a hand lever pivoted to the other end of the bolt and a cam surface on said lever coacting with the other jaiw, the locking bolt being slotted to permit its movement relative to a fixed pivot carrying a roller cooperating with the cam for efiecting clamping movement of the bolt.

2. A clamping device for the head-rests of dental or like chairs comprising a support having split jaw members at each end in which are carried the pivots of the chair bracket and headrest arm respectively, a locking bolt housed in a longitudinal bore in the support and secured at one end to a nut in one jaw of one of the split jaw members and carrying at its other end a pivoted hand lever actuating a cam co-operating with a roller on a pivot fixed in the remote jaw of the other split jaw member.

3. A clamping device according to claim 2 in which means are provided for imposing a slight frictional resistance on the clamping member housing the pivot of the chair bracket.

4. A clamping device according to claim 2 in which the locking bolt is slotted to take the pivot on which is mounted the roller co-operating with the cam.

FRANK MOORE COWPER. 

